Test S - System Check
Perform this test only after Code 11 is displayed in KOEO Self-Test and you have been directed here from TEST A, step 20) or by a driveability symptom.
- ISC by-pass air system
- MAP system
- EGR system
- MAP system
To prevent the replacement of good components, be aware that the following non-EEC-IV areas may be at fault:
- Faulty power or ground connections
- Ignition system (distributor cap, rotor, wires, coil, plugs)
- Basic mechanical engine components (cam timing, compression, etc.)
1) ISC-BPA Check This step is for PFI vehicles with stall or no start faults. If engine stalls or if it does not start, attempt to start engine at part throttle. If engine will start and run smoothly at part throttle, go to TEST KE, step 4). If not, proceed to step 3).
2) Check For RPM Drop Turn key off. Connect a tachometer. Start engine and disconnect ISC solenoid. If RPM drops or engine stalls, reconnect ISC solenoid and go to next step. If not, go to step 4).
3) Power to MAP/BP Sensor If vehicle is not equipped with a MAP/BP sensor, go directly to step 8). Use Ford Motor Co. MAP/BP tester for this test. If Green light is on, VREF circuit voltage is okay. If Red light (or no light) is on, VREF circuit voltage is too low or too high. Turn key off and disconnect MAP/BP sensor from vehicle harness. Connect MAP/BP tester between vehicle harness and MAP/BP sensor. Connect banana plugs of tester into DVOM and set DVOM on 20-volt scale. With tester connected, turn key on. If Green light is on, go to next step. If light is not on, repair open in VREF circuit, remove MAP/BP tester. Reconnect components and retest symptom.
4) MAP/BP Tester Output Reading Measure several known good MAP sensors to obtain average measured voltage for specific location and date of testing. With MAP/BP tester and DVOM connected. Turn key on and measure MAP/BP SIG voltage at MAP sensor. If voltage is in the correct range for altitude, go to next step, except vehicles equipped with MA sensors, go to step 8). If voltage is not in the correct range for altitude, replace MAP/BP sensor.
| Approximate Elevation (Ft.) | Output In Volts |
|---|---|
| 0 | 1.55-1.63 |
| 1000 | 1.52-1.60 |
| 2000 | 1.49-1.57 |
| 3000 | 1.46-1.54 |
| 4000 | 1.43-1.51 |
| 5000 | 1.40-1.48 |
| 6000 | 1.37-1.45 |
| 7000 | 1.35-1.43 |
5) Check MAP/BP Sensor Turn key off and wait 10 seconds. Disconnect vacuum line from MAP sensor. Install vacuum pump to MAP sensor. Apply 18 in. Hg vacuum to MAP sensor. If MAP sensor holds vacuum, release vacuum and remove vacuum pump. Reconnect vacuum line to MAP sensor and go to next step.
6) MAP Engine Running Response Test Turn key on. Ensure MAP/BP tester and DVOM are connected. Set DVOM on 20-volt scale. Crank engine. If MAP output voltage changes while engine is being cranked, go to step 8). If not, go to next step.
7) Check Vacuum Lines Check vacuum lines for correct routing. Refer to VECI decal. Check MAP sensor vacuum line for leaks or blockage. If vacuum lines are okay, replace MAP sensor. Remove MAP/BP tester. Recheck system operation. If vacuum lines are not okay, repair as necessary. Rerun QUICK TEST.
8) Check EGR Vacuum If vehicle is not equipped with EGR system hardware, go directly to TEST H, step 1). Steps No. 8 and 9 attempt to determine if EGR system is cause of driveability symptom or NO START. Disconnect vacuum line at EGR valve. DO NOT plug vacuum line. Start engine. If vehicle was a NO START, and still does not start, or if vehicle had a driveability fault, and vacuum is NOT present at EGR vacuum line, go to next step. If vehicle still a NO START, or vacuum is not present, go to the following appropriate CIRCUIT TEST:
- 3.0L SHO PFI: Go to TEST DL, step 21)
9) Check EGR Valve Inspect EGR valve for leaks. If valve is fully closed, go to TEST H, step 1). If EGR valve is leaking or not fully seated, replace or repair valve.